ISSN 2336-3193 Acta Mus. Siles. Sci. Natur., 69: 161-164, 2020 DOI: 10.2478/cszma-2020-0011 Published: online 1 July 2020, print July 2020 A new species of Systenus Loew (Dolichopodidae, Diptera) from Slovakia Oleg P. Negrobov, Peter Manko & Jozef Oboňa A new species of Systenus Loew (Dolichopodidae, Diptera) from Slovakia. – Acta Mus. Siles. Sci. Natur. 69: 161-164, 2020. Abstract: Dolichopodid specimens were collected during a field work in Prešov town in 2019. Systenus slovakiensis sp. nov. from anthropogenic habitats is described. Differential diagnoses are given and illustrated. A key to females of Systenus species of the Palearctic is provided. From all other Palaearctic species of this genus, the new species is distinguished by snow-white trochanters and black femora. Key words: Taxonomy, new species, Systenus, Slovakia, Palaearctic Region Introduction The genus Systenus Loew, 1857 was separated by Loew from the genus Rhaphium Megen, 1803. Rhaphium adpropinquans Loew, 1857, which is a synonym of Systenus pallipes (von Roser, 1840), was designated as the genus type in the catalogue of North American dipterans (Foote et al. 1965). 37 species of this genus are known in the world fauna (e.g. Naglis 2000, 2017, Yang & Gaimari 2004, Yang et al. 2006, Grichanov & Mostovski 2009, Bickel 2015). Currently 11 species are known for the Palearctic (Kassebeer 1998, Negrobov 2005, Naglis 2017). This genus was placed into a separate subfamily Systeninae (Negrobov 1991), although some authors placed Systenus in the subfamily Medeterinae (Bickel 1986, 2015). Species of this genus live on tree trunks. The larvae develop in debris of tree-holes. The larvae possess two large ventral false legs on the first abdominal segment which is unique in all known dolichopodid larvae. The preimaginal stages of several North American species were described by Wirth (1952). Krivosheina (1973) provides a key to the larvae of three Palearctic species of this genus (S. bipartitus (Loew, 1850), S. pallipes (von Roser, 1840), and S. scholzi (Loew, 1850)). Representatives of Systenus are relatively rare in forest ecosystems, and in results of colle- cting activities in nature females are much more common. Most Palaearctic species are known mainly from Western Europe (Negrobov 2005). From Slovakia 3 species are known of the genus Systenus (Oboňa et al. 2012) and the species list of long-legged flies of Slovakia includes 245 taxa (Pollet & Suvák 2009, Oboňa et al. 2012, Maslova et al. 2018, Negrobov et al. 2019). Systenus slovakiensis sp. nov. increases the number of Slovakian Dolichopodidae to 246 spe- cies. Material and methods The material has been collected by Oboňa and Manko in Prešov town in Slovakia. One female of Systenus was captured by hand from tree trunks (Acer sp., Tilia sp., Fraxinus sp.) in anthropogenic habitats in town together with other Medeterinae and preserved in 96% ethanol. Morphological terminology follows Cumming & Wood (2009). The type is stored in the collection of Zoological Institute of the Russian Academy of Sciences (St. Petersburg). 161 Taxonomy Family Dolichopodidae Genus Systenus Loew, 1857 Systenus slovakiensis Negrobov, Manko & Oboňa sp. nov. (Figs 1-4) Description. Female. Body length (holotype): 2.0 mm, wing length 2.1 mm. Head. Frons metallic green without pollen. Face dark green, without pollen. Antennae black (Fig. 1). Length of postpedicel greater than width, arista longer than postpedicel. Ratio of length of postpedicel to its width and length of arista is 2.3: 1.8: 2.8. Palpus and proboscis dark brown. Postocular setae yellow below. Thorax. Dark metallic green. Mesoscum dark green with two narrow longitudinal bronze stripes. Propleuron below with black seta. 6 pairs of dorsocentral setae. Acrostichial setae arranged in two rows, 10-11 pairs. Scutellum with 2 strong marginal setae and 2 hairs on the sides of the scutellum. Legs. Coxae and femora black with metallic green reflections (Fig. 3), trochanters snow- white, femora in narrow distal part, tibiae and tarsi yellow. Femora without strong setae. Ratio of length of fore tibia to length from 1st to 5th segments of fore tarsus is 5.1: 2.0: 1.2: 0.9: 0.8: 0.7. Mid and hind femora without long hairs. Mid tibia with 1 anterodorsal and 1 posterodorsal setae. Ratio of length of mid tibia to length from 1st to the 5th segments of middle tarsi is 6.3: 2.7: 1.7: 1.5: 0.8: 0.6. Hind tibia with 2-3 short dorsal setae. Ratio of length of hind tibia to length from 1st to the 5th segments of hind tarsi is 6.5: 1.8; 2.5: 1.5: 1.0: 0.5. Wing. Transparent with dark veins (Fig. 2). Ratio of length of costal vein between R 2 + 3 and R 4 + 5 and between R 4 + 5 and M is 1.6:1.5. R 4 + 5 and M at apex parallel. Apical segment of CuA longer than dm-cu crossvein - 1.8:1.2. Halter yellow. Lower calypter yellow with yellow bristles. Abdomen. Dark green shiny with bronze reflections, with black hairs. Male. Unknown. Type material. Holotype ♀ (Fig.4): Slovakia, Prešov town, 250 m a.s.l., 48°59'50.1"N 21°13'19.2"E, August 2019, hand collected from tree trunks (Acer sp., Tilia sp., Fraxinus sp.) in anthropogenic habitats, leg. Oboňa and Manko. Deposited in in the collection of the Zoological Institute of the Russian Academy of Sciences (St. Petersburg). Etymology. Named after the country where the species was collected. Differential diagnosis. The new species is close to Systenus bipartitus and S. leucurus, from which it differs by the black femora, chaetotaxy of the mid tibia and different length of the arista. From all other Palaearctic species of this genus, the new species is distinguished by snow-white trochanters and black femora. Key of female species of Systenus of the Palearctic 1. R4 + 5 and M to the apex sharply converging ………….………….……………………………………… 2 - R4 + 5 and M to the apex almost parallel ………………………….…………………………………..… 4 2. Scape and pedicel dark ……………………………………………... Systenus pallipes (von Roser, 1840) - Scape and pedicel yellow, postpedicel brown dorsally……………………………………………….… 3 3. Abdomen dark. Postpedicel approximately 1.5 times as long as wide, darkened at apex and on dorsal side. Section of costal vein between R 2 + 3 and R 4 + 5 approximately 3.5 times longer than section of costal vein between R 4 + 5 and M …………………………………………………… Systenus scholtzii (Loew, 1850) - Abdomen with yellow spots at base. Postpedicel approximately 2 times as long as wide, darkened only on dorsal side. Section of costal vein between R 2 + 3 and R 4 + 5 approximately 2 times longer than section of costal vein between R 4 + 5 and M …………………………... Systenus flavimaculatus Negrobov, 2005 4. Antennae yellow …………………………………………………………….... Systenus tener Loew, 1859 - Antennae mainly dark ………………………………………………………………..………………… 5 5. Femora mainly black, with yellow apex. Middle tibia with 2 setae at base. Arista barely exceeds length of postpedicel …………………………………………………….………..… Systenus slovakiensis sp. nov. - Femora mainly yellow, with black apex ……………………………………………………………….. 6 6. Arista barely exceeds length of postpedicel. Middle tibia with 2 setae at base……………………….. ………………………………………………………………………………..….. Systenus bipartitus (Loew, 1850) - Arista about 2 times as long as postpedicel. Middle tibia with 4 setae at base…………………………… …………………………………………………………………………….. Systenus leucurus Loew, 1859 162 Figs 1–2: Systenus slovakiensis Negrobov, Manko & Oboňa sp. nov. female. 1 – Antenna, 2 – Wing. [Scale: 1 = 0,5 mm; 2 = 1 mm] Figs 3–4: Systenus slovakiensis Negrobov, Manko & Oboňa sp. nov. 3 – Leg, 4 – Habitus. [Scale: 3, 4 = 1 mm] 163 Acknowledgements: We thank the editor and all anonymous reviewers for their valuable and constructive comments on the first version of the manuscript. The work of O. P. Negrobov was supported by the Russian Foundation for Basic Research according to the research project № 20-54-53005 and by the National Natural Science Foundation of China. The work of J. Oboňa and P. Manko was supported by the Slovak Research and Development Agency under the contract No. APVV-16-0236 and by the Slovak Scientific Grant Agency, contract No. VEGA-1/0012/20. References Bickel D.J. (2015): The Costa Rican Systenus Loew (Diptera: Dolichopodidae): rich local sympatry in an otherwise rare genus. – Zootaxa 4020(1): 169-182. – (1986): Australian species of Systenus (Diptera: Dolichopodidae). – Records of the Australian Museum 38: 263-270. Cumming J.M. & Wood D.M. 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